Acylthiomethyl esters of cephalosporins

ABSTRACT

WHEREIN R1 is hydrogen, lower alkyl, cycloalkylmethyl, cycloalkenylmethyl, cycloalkadienylmethyl, aryloxymethyl, aralkyl, certain heterocyclic groups and certain substituted members of such groups; R2 is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl and R3 is lower alkyl, lower alkenyl, aryl or aralkyl. X is hydrogen, hydroxy, lower alkanoyloxy, aroyloxy, lower alkoxy, aralkanoyloxy, the radical of a nitrogen base, a quarternary ammonium radical, lower alkylmercapto or certain heterocyclic substituted mercapto groups. They are useful as antibacterial agents.   D R A W I N G New acylthiomethyl esters of cephalosporins have the formula

United States Patent [191 Breuer Jan. 14, 1975 1 ACYLTHIOMETHYL ESTERS OF CEPH ALOSPORINS [75] lnventor: Hermann Breuer,Regensburg,

Germany [731 A ssignec: E. R. Squibb & Sons, Inc.,

Princeton, NJ.

[22] Filed: Aug. 3, 1972 [21] Appl. No.: 277,700

Primary ExaminerNicholas S. Rizzo Attorney, Agent, or FirmLawrence S. Levinson; Merle J, Smith [57] ABSTRACT New acylthiomethyl esters of cephalosporins have the formula I/ S R -CONH r-f l 4 L cn x COOCHSCOR3' wherein R, is hydrogen, lower alkyl, cycloalkylmethyl, cycloalkenylmethyl, cycloalkadienylmethyl, aryloxymethyl, aralkyl, certain heterocyclic groups and certain substituted members of such groups; R is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl and R is lower alkyl, lower alkenyl, aryl or aralkyl. X is hydrogen, hydroxy, lower alkanoyloxy, aroyloxy, lower alkoxy, aralkanoyloxy, the radical of a nitrogen base, a quarternary ammonium radical, lower alkylmercapto or certain heterocyclic substituted mercapto groups. They a re useful as antibacterial agents.

10 Claims, N0 Drawings ACYLTHIOMETHYL ESTERS OF CEPHALOSPORINS BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION This invention relates to new acylthiomethyl esters of cephalosporins having the formula R1CO-NH f R is hydrogen, lower alkyl, cycloalkylmethyl, like cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl or cyclohexylmethyl, cycloalkenylmethyl, monounsaturated cycloaliphaticslike the foregoing cycloalkylmethyl groups, cycloalkadienylmethyl like cyclopentadienylmethyl or cyclohexadienylmethyl, aryloxymethyl like phenoxymethyl, aralkyl, e.g., phenyllower alkyl or the same groups with simple substituents on the phenyl, cyanomethyl, azidomethyl, and certain heterocyclic groups like furylmethyl, thienylmethyl, oxazolylmethyl, thiazolylmethyl, isoxazolylmethyl, oxadiazolylmethyl, thiadiazolylmethyl, tetrazolylmethyl, pyridylthiomethyl, and such groups simply substituted. Members of the foregoing groups substituted on the a-carbon atom with an amino, hydroxy, carboxy, ureido, lower alkanoylureido, sulfonylureido, sulfonyl or sulfonylamido groups are also included. R is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl. R represents lower alkyl, lower alkenyl, aryl, halophenyl,

benzhydryl or aralkyl groups such as those described above. X is hydrogen,.hydroxy, lower alkanoyloxy, aroyloxy, lower alkoxy, aralkanoyloxy, the radical of a nitrogen base such as alkylamines or aralkylamines, quaternary ammonium radicals likepyridinium, quinolinium, picolinium and the like, lower alkylthio, certain heterocyclic substituted mercapto groups like oxazolythio, thiadiazolylthio, thiatrizolythio or lower alkyl substituted members of this group.

When R is a basic substituent the products form acid addition salts which are also within the scope of the invention.

The preferred members of the group are those wherein R, is benzyl, phenoxymethyl, a-substituted benzyl, especially wherein the a-substituent is amino, hydroxy, carboxy or ureido, thienylmethyl, and a-substituted thienylmethyl especially wherein the a-substitlower alkyl, especially methyl, substituted members of the last two.

DETAILED DESCRIPTION OF THEINVENTION The various groups represented by the symbols have the meanings defined below and these definitions are retained throughout this specification.

The lower alkyl groups are straight or branched chain hydrocarbon'radicals having one to eight carbons in the chain, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, amyl or the like. The lower alkenyl groups are monounsaturated groups like those first described, the two to four carbon members being preferred.

The aryl groups are monocyclic carbocyclic aryl groups including simply substituted members. By way of illustration, this includes the phenyl ring and simply substituted phenyl containing one to three substituents (preferably only one) such as the halogens (chlorine and bromine being preferred), lower alkyl groups such as those defined above, lower alkoxy groups, (i.e., lower alkyl groups of the type defined above attached to an oxygen), hydroxy, amino, carboxy and the like. In the case of the last two named substituents there is preferably only one, especially in the para position of the phenyl.

The aralkyl groups include a monocyclic carbocyclic aryl group attached to a lower alkyl group, both as defined above, benzyl being preferred.

The cylo-lower alkyl groups are the alicyclics of three to six carbon atoms, e.g., cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl; cyclopentyl and cyclohexyl are preferred. The cyclo-lower alkenyl groups are the 4 to 6 carbons monounsaturated cyclic groups including cyclobutene, cyclopentene and cyclohexene. The cyclo-lower alkadiene groups are similar cyclic groups which have two double bonds, particularly cyclohexadienyl and especially 1,4-cyclohexadienyl. All of these are attached to a bridging methylene group.

The heterocyclic groups represented by R arev the heterocyclic radicals thienylmethyl, furylmethyl, oxazolylmethyl, isoxazolylmethyl, oxadiazolylmethyl, thiadiazolylmethyl, tetrazolylmethyl and thiazolylmethyl, as well as these heterocyclics with the substituents halo, lower alkyl (particularly methyl and ethyl), lower alkoxy (particularly methoxy and ethoxy) or phenyl, and thienylmethyl having amino, hydroxy, carboxy or ureido as an a-substituent;

In addition, the R groups, especially those with a cyclic substituent, may be substituted on the a-carbon atom. These include hydroxy, amino, carboxy, ureido, lower alkanoylureido, sulfonylureido, sulfonyl or sulfonylamido.

The lower alkanoyloxy, aroyloxy and aralkanoyloxy groups represented by X include the acyl group of acid esters. The lower alkanoyl radicals are the acyl radicals of lower fatty acids containing alkyl radicals of the type described above. The lower alkanoyloxy groups include, for example, acetoxy, propionyloxy, butyryloxy and the like. The aroyloxy groups are derived from monocyclic carbocyclic aryl groups of the kind described. Similarly the aralkanoyloxy groups consist of monocyclic carbocyclic aryl and alkanoyloxy radicals of the type described. X also represents the radical of an amine, e.g., an alkylamine like methylamine, ethylamine, dimethylamine, triethylamine, aralkylamine like dibenzylamine, N,N-dibenzylpyridinium, pryidinium, l-quinolinium, l-picolinium, etc. The lower alkylmercapto groups represented by X include, for example, methylmercapto, ethylmercapto, propylmercapto and the like. The mercapto group may in addition bear one of the heterocyclic radicals oxadiazolyl, thiadiazolyl, tetrazolyl or thiatriazolyl, these heterocyclics may also bear a lower alkyl group, preferably methyl.

The compounds described above are essentially neutral, when R however, is a basic group, a-aminobenzyl for example, acid addition salts of the conventional type are formed, e.g., hydrohalides like the hydrochloride, other inorganic acid salts like the sulfate, phosphate, organic salts like the citrate, benzenesulfonate, toluensulfonate, etc.

The new compounds of this invention may be synthesized by several methods.

According to one method the carboxy group of a cephalosporin of the formula (II) R -CO-NH CHX C OOH is first converted to an activated derivative. This activated derivative is preferably formed by treatment with dicyclohexylcarbodiimide, but may also be the reaction product with an anhydride forming agent such as ethylchloroformate, benzoyl chloride, pivaloyl chloride, etc., or with bis-imidazolecarbonyl, p-nitrophenol and the like. The activated derivative of the compound of formula II is made to react with an acylmercaptomethanol derivative of the formula $2 3-C-S-CH-OH This reaction is effected at a temperature in the range of about C. to ambient temperature in an inert organic solvent such as tetrahydrofuran, dimethylformamide, dimethylacetamide, acetone, dioxane or the like and a product of formula 1 results.

Alternatively, a salt of a cephalosporin 0f the formula COOY (III) 0 II is made to react with a compound of the formula (v) ,2

hal-CH-S-COR R R R and X have the same meaning as above, Y is a cation, e.g., a metal cation such as the alkali metal cations sodium and potassium, or the cation of a nitrogen base such as the ammonium ion, trialkylammonium ions, etc, and hal is a halogen, cspccially chlorine or bromine.

This reaction is effected at a temperature of about 0 to 50C., preferably in a suitable inert organic solvent R -c0sH n cao (VI) (VII) 0' R ll l (II n -c-s-cn-oa l h alogenation R h l g (V) R -CS-CHhal The synthesis of the new acylthiomethyl esters of penicillins of formula I may also be effected from what!- oalkyl esters of cephalosporanic acid derivatives of the formula R -CO-N'H N CH X COOCH-hal (VIII) The compound of formula VIII is reacted with a salt, for example, an alkali metal salt, of a compound of formula VI above in an inert organic solvent, such as those named previously, at a temperature of about 0 to 50C., preferably at room temperature.

The compounds of formula I may also be produced by acylating a compound of the formula s HZN CH X or a salt thereof with a reactive derivative of the acid R COOH. Such derivatives include, for example, acid halides, acid anhydrides, mixed anhydrides of the acid with, for-example, carboxylic acid monoesters, trimethylacetic acid or benzoic acid, acid azides, active esters such as cyanomethyl ester or p-nitrophenyl ester or active amides such as acylimidazoles.

The acid R -COOH may also be reacted with a compound of formula lX in the presence of a carbodiimide, for example, N,N'-dicyclohexylcarbodiimide, or

an isoxazole salt such as N-cthyl-5-phenylisoxazolium- 3-sulfonate, or 2-eth0xy-l,2-dihydroquinolinc-lcarboxylic acid ethyl ester.

The compounds of formula IX are also new, and may be produced, for example, by the reaction of a compound of the formula N /--CH2X COOY with a compound of formula V above. This reaction is effected at a temperature within the range of about 0 to 50C., preferably about room temperature, in an inert solvent such as dimethylformamide.

The compounds of formula IX may also be produced from compounds of formula I, especially when R is a selected substituent such as benzyl or phenoxymethyl, by converting this particular compound of formula I with phosphorus pentachloride under anhydrous conditions to an imide chloride of the formula COOCH-S COR Then, by treating the product of formula X1 with certain alcohols, e.g., methanol or isopropanol, and further with water, the product of formula 1X optimally in the form of its salt, such as the hydrochloride or tosylate, is obtained. By forming the salt the molecule is stabilized and more readily isolated.

Further process details are also provided in the illustrative examples.

Certain of the compounds of this invention may exist in different optically active forms. The various stereoisomeric forms as well as the racemic mixtures are within the scope of the invention.

The compounds of this invention have antibacterial activity against both gram positive and gram negative organisms such as Staphylococcus aureus, Salmonella schottmuelleri, Pseudomonas aeruginosa, Proteus vulgaris, Escherichia coli and Streptococcus pyogenes. They may be used as antibacterial agents in a prophylactic manner, e.g., in cleaning or disinfecting compositions, or otherwise to combat infections due to organisms such as those named above. They also show activity against fungi like Candida albicans. For example, a compound of formula I or a physiologically acceptable salt thereof may be used in various animal species in an amount of about 3 to 100 mg./kg., daily, orally or parenterally, preferably orally, in single or two to four divided doses to treat infections of bacterial origin, e.g., 4.0 mg./kg. in mice.

Up to about 500 mg. of a compound of formula I or a physiologically acceptable salt thereof may be incorporated in an oral dosage form such as tablets, capsules or elixirs or in an injectable form in a sterile aqueous vehicle prepared according to conventional pharmaceutical practice.

They may also be used in cleaning or disinfecting compositions, e.g., for cleaning barns or dairy equipment, at a concentration of about 0.01 to 0.5% by weight of such compounds admixed with, suspended or dissolved in conventional inert dry or aqueous carriers for application by washing or spraying. They are also useful as nutritional supplements in animal feeds.

The following examples are illustrative of the invention. All temperatures are on the centigrade scale. Ad ditional variations may be produced in the same manner by appropriate substitution in the starting material.

EXAMPLE 1 21.4 g. (0.05 mol.) of the potassium salt of 7- (phenylacetamido)cephalosporanic cephalosporanic acid, 8.45 g. (0.05 mol.) of (bromomethyl)acetylsu1- fide and 200 ml. of anhydrous dimethylformamide are stirred for 48 hours at room temperature with the exclusion of moisture. The reaction mixture is poured, with stirring into 1 liter of ice water, treated with ethyl acetate and the aqueous phase is shaken twice more with ethyl acetate. The combined ethyl acetate extracts are washed five times with water, decolorized with activated carbon, dried with magnesium sulfate and the solvent then driven off in vacuo in a rotary evaporator. The crude yield is 21.2 g. of a viscous syrup.

The crude product is purified by dissolving in methylene chlorideand the solution is chromatographed in a silica gel column. The product is eluted from the column with a mixture comprising 2 parts of methylene chloride and 1 part tetrahydrofuran. After concentrating, there are obtained 12.8 g. of residue, which solidities upon trituration with ether. The product thus obtained, the (acetylthio)methyl ester of 7- (phenylacetamido)cephalosporanic acid, melts at 100. 1

The following additional products are made by the procedure of Example 1 by substituting for the bromomethylsulfide the appropriately substituted sulfide.

11 v 12 Continued Example R R R X H I N CH N -S-CH2 H CI-I2CH2CH3 -SCH3 34 Q z H z s 3 H CH- 35 \L CH 3 CH H S NHCONH 36 Q H CH 5 H CH H NH2 Q 2 39 OCH H 3 -OCOCH COOH 41 I (FH- CH3 CH OCOCH ll 5 I OH 4 2 CH 3 H H What is claimed is: benzyl bearing on the a-carbon amino, hydroxy, car- I. A compound of the formula boxy or ureido.

3. A compound as in claim 1 wherein R is phenoxy- R CONH 5 y l 4. A compound as in claim 1 wherein R is hydrogen N CH X and R is lower alkyl.

5. A compound as in claim 1 wherein R is benzyl, R 0 F is hydrogen, R is methyl and X is acetoxy.

6. A compound as in claim 1 wherein R is benzyl, R COOCH SCOR3 is hydrogen, R is methyl and X is hydrogen.

wherein R is phenoxymethyl, phenyl-lower alkyl, and phenyl-lower alkyl bearing on the a-carbon hydroxy, amino carboxy, or ureido, R is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl, R is lower alkyl, lower alkenyl, phenyl, or phenyl-lower alkyl, X is hydrogen, hydroxy, or lower alkanoyloxy, and acid addition salts of the basic members thereof.

2. A compound as in claim 1 wherein R is benzyl or 7. A compound as in claim 1 wherein R is a-aminobenzyl, R is hydrogen, R is methyl and X is hydrogen.

8. A compound as in claim 1 wherein R is benzyl, R is hydrogen, R is phenyl and X is hydrogen.

9. A compound as in claim 1 wherein R is phenoxymethyl, R is hydrogen, R is methyl and X is acetoxy.

10. A compound as in claim 1 wherein R is benzyl, R is hydrogen, R is t-butyl and X is hydrogen. 

2. A compound as in claim 1 wherein R1 is benzyl or benzyl bearing on the Alpha -carbon amino, hydroxy, carboxy or ureido.
 3. A compound as in claim 1 wherein R1 is phenoxymethyl.
 4. A compound as in claim 1 wherein R2 is hydrogen and R3 is lower alkyl.
 5. A compound as in claim 1 wherein R1 is benzyl, R2 is hydrogen, R3 is methyl and X is acetoxy.
 6. A compound as in claim 1 wherein R1 is benzyl, R2 is hydrogen, R3 is methyl and X is hydrogen.
 7. A compound as in claim 1 wherein R1 is Alpha -aminobenzyl, R2 is hydrogen, R3 is methyl and X is hydrogen.
 8. A compound as in claim 1 wherein R1 is benzyl, R2 is hydrogen, R3 is phenyl and X is hydrogen.
 9. A compound as in claim 1 wherein R1 is phenoxymethyl, R2 is hydrogen, R3 is methyl and X is acetoxy.
 10. A compound as in claim 1 wherein R1 is benzyl, R2 is hydrogen, R3 is t-butyl and X is hydrogen. 